Patent GB-1467891-A (GB)
Title: Locking system
IPC: G07C9/00
Filed: 1974-01-23
Abstract: 1467891 Multiple code accepting locks PITNEY BOWES INC 23 Jan 1974 03145/74 Heading E2A A lock at a given instant, accepts two codes, one of which, when applied after application of the other, causes the lock to henceforth reject the other code and replace it by a new acceptance code this rejection and replacement being operable repetitively. Fig. 1 shows a hotel room lock which accepts the codes on suitable keys to produce electronic signals, although a keyboard could be used by personnel using oral or numeric information. A guest will have a key 12 which causes a register 14 to transmit a digital code signal which is compared in any. of comparators 18, 20, 22, 24 with different codes emanating from a function generator 26. If a matching comparison is made in the comparator 18, signal passes through an OR-gate 40 to operate a lock mechanism 44; however if a signal emanates from the comparator 24 instead, not only is the lock mechanism 44 operated but a signal passes to the generator 26 whereby the code which originally passed to the comparator 18 is removed, the code which went to the comparator 24 now passes to the comparator 18, and a new code is generated for the comparator 24. This ensures that when a new guest operates the lock, the previous guest cannot gain access henceforth. Different codes on keys used by maids also operate the lock in a similar manner where comparators 20, 22 are analogous to the comparators 18, 24 respectively; these maid codes would be common for a series of hotel room locks. A guest key 12 may have a code which causes an output from a comparator 50 to set a flip-flop 54 to inhibit the comparators 20, 22 from providing lock mechanism operating signals to prohibit maid entry. This inhibition is. removed by subsequent normal code key operation which, via an OR-gate 58, resets the flip-flop 54. Keys 12 with special codes may operate one of two comparators 66, 68 (for guest and maid codes respectively) to reset the function generator 26 to provide a known code at its respective comparators 18, 24 or 20, 22. The function generator 26 has two identical circuits, for guest and maid codes respectively. In each, a register provides a code which is the reference code in comparator 18 or 20, the signal passing to an adder which adds thereto a code from a further register to provide the code for the comparator 22 or 24 which also passes to a multiplexer. When the key 12, bearing the code which operates the comparator 22 or 24, is operated, the output from the comparator causes the first register to accept the code of the multiplexer and transmits this code now to the comparator 18 or 20, a new code being produced by the adder for the comparator 22 or 24. When a reset key is operated, its code is transmitted to the multiplexer which accepts this code if the comparator 66 or 68 provides a signal, which also causes the first register to accept the multiplexer code for the comparator 18 or 20. The further register which produces an arithmetic code series, may be replaced by component(s) producing a trigonometric, logarithmic, or random number series. Internal deviation of the reset codes may be achieved, thus obviating the external operation. In Fig. 2, a central keyboard 80, e.g. at a hotel desk has a random access memory 82 which provides the required codes for each hotel room, if the room number is called up on the keyboard. For a new guest (or maid) the codes for the comparator 18 or 20 is retrieved, this code being transmitted to a function generator 86 which, as with the generator 26 provides the code for comparator 22 or 24; this is supplied to a key maker 84 to produce a correctly coded key. If a duplicate key, a maid lockout key, or a reset key is required, a switch 88 is closed for direct code transmission from the memory 82. For the reset codes; a switch 90 is closed so that the memory stores these as the new codes.